Image projection system

ABSTRACT

A system for use in retinal image projection comprising at least first and second image projection units and an eye projection optical module. The projection units are configured and operable for projection of at least first and second image portions respectively. The eye projection optical module is optically coupled to the image projecting units and is configured and operable to combine optical paths of projection of the at least first and second image projection units along a general optical path. Thus providing light beams from the first and a second image projection units, associated with projection of first and a second image portions respectively, to be directed to propagate towards a user&#39;s eye to project a combined image of the first and second image portions on the retina.

TECHNOLOGICAL FIELD

The present invention is in the field of image projections systems andis particularly related to wearable/head mounted retinal projectionsystems for providing a pure, augmented or virtual reality experience tousers.

BACKGROUND

Head mounted or generally wearable image projection systems are used forproviding virtual and/or augmented reality experience by displayingimages directly into users' eyes. Various types of head mountedprojection systems are known utilizing image projection in front of orinto the eyes of a user. Such projection systems are in many casesconfigured as glasses mountable onto a user's head and operable forprojecting images onto the user's eyes for providing true and convincingdisplay.

Similar to standard display systems, head mounted display systems aim toprovide high resolution images while utilizing limited computationalpower. To simplify image rendering complexity, certain retinal/fovealdisplay systems have been developed, utilizing separate imageprojections for the foveal region of the user's eye, and an additional,lower resolution image projection directed to the peripheral regions ofthe retina to provide a wide field of view.

US2008002262 discloses a head mounted display device which has a mountwhich attaches the device to a user's head, a beam-splitter attached tothe mount with movement devices, an image projector which projectsimages onto the beam-splitter, an eye-tracker which tracks a user'seye's gaze, and one or more processors. The device uses the eye trackerand movement devices, along with an optional head-tracker, to move thebeam-splitter about the center of the eye's rotation, keeping thebeam-splitter in the eye's direct line-of-sight. The user simultaneouslyviews the image and the environment behind the image. A secondbeam-splitter, eye-tracker, and projector can be used on the user'sother eye to create a stereoptic, virtual environment. The display cancorrespond to the revolving ability of the human eye. The inventionpresets a high-resolution image wherever the user looks.

US 2012/0105310 describes a head mounted display system with at leastone retinal display unit having a curved reflector positioned in frontof one eye or both eyes of a wearer. The unit includes a first set ofthree modulated visible-light lasers co-aligned and adapted to provide alaser beam with selectable color and a first scanner unit providing bothhorizontal and vertical scanning of the laser beam across a portion ofthe curved reflector in directions so as to produce a reflection of thecolor laser beam through the pupil of the eye onto a portion of theretina large enough to encompass the fovea. The unit also includes asecond set of three modulated visible-light lasers plus an infraredlaser, all lasers being co-aligned and adapted to provide a color andinfrared peripheral view laser beam, and a second scanner unit providingboth horizontal and vertical scanning of the visible light and infraredlaser beams across a portion of the curved reflector in directions so asto produce a reflection of the scanned color and infrared laser beamsthrough the pupil of the eye onto a portion of retina corresponding to afield of view of at least 30 degrees×30 degrees.

US 2005/185281 describes an apparatus for viewing which includes ascreen. The apparatus includes means for detecting a fixation point of aviewer's eyes on an image on the screen. The apparatus includes meansfor displaying a foveal inset image of the image on the screen about thefixation point so a viewer's fovea sees the foveal image while the restof the eye sees the image. The method includes the steps of detecting afixation point of a viewer's eyes on an image on a screen. There is thestep of displaying a foveal inset image of the image on the screen aboutthe fixation point so the viewer's fovea sees the foveal image while therest of the eye sees the image.

US 2009/189830 describes a display device which is mounted on and/orinside the eye. The eye mounted display contains multiple sub-displays,each of which projects light to different retinal positions within aportion of the retina corresponding to the sub-display. The projectedlight propagates through the pupil but does not fill the entire pupil.In this way, multiple sub-displays can project their light onto therelevant portion of the retina. Moving from the pupil to the cornea, theprojection of the pupil onto the cornea will be referred to as thecorneal aperture. The projected light propagates through less than thefull corneal aperture. The sub-displays use spatial multiplexing at thecorneal surface.

GENERAL DESCRIPTION

There is a need in the art for a novel configuration of a display systemproviding retinal image projection having desirably highimage/projection quality with given image rendering power.

In conventional projection systems the maximal image resolution isgenerally limited by several factors: image generating element(projecting unit), processing power provided by the control unit, e.g.graphic processing unit (GPU), and bandwidth of data transmission fromthe GPU to the projecting unit(s). Thus, providing image projection,having pixel density equivalent to spatial resolution of human visionutilizing conventional eye projection systems, requires both extremelyhigh computing power and may typically require an array of smallprojecting/display units.

More specifically, providing imaging with maximal human eye resolutionmay typically require projection of image frames containing about 20megapixels or more for each eye. Additionally, to provide temporalresolution matching to that of human perception (so that image movementsare perceived as smooth and seamless), the displayed images may need tobe rendered at rates of 60 HZ or more. This requires high rates of imagerendering and of data transfer between the control unit and theprojecting unit(s), and between a storage utility and the control unit(e.g. in the order of 28 GBit/second considering projection of imageswith color depth of 24 bit color). Such high data transfer rates aregenerally beyond the capabilities of state of the art eye projectiondevices, and in any case, might increase the systems' weight, size, costand energy consumption.

The present invention provides a novel image projection system whichutilizes two or more image projection modules/units to project image(s)with spatially varying image projection quality onto the retina. In thisregard, the phrase image projection quality is used herein to refer tothe pixel density (e.g. DPI or dots per unit solid angle) of the imageprojection onto the retina, and possibly also onto the color depth levelin the projected image. To this end, in some embodiments the two or moreprojection modules provide image portions having respectively two ormore levels of color depth.

In certain embodiments, the technique of the present invention utilizesprojection of high pixel density image portions, i.e. having highangular resolution and equivalently high number of dots per inch (DPI)on the projected surface, onto the fovea region of a user's eye andprojection of image portions with lower pixel density (lowerangular-resolution/DPI) onto the periphery of the user's retina (e.g.the parafoveal region). This provides effective high resolutionperception of the projected image by the user's eye, while reducingimage rendering, data transmission and storage needs of the projectionsystem. Thus, high pixel density image(s) are provided to retina regions(fovea) which are capable of collecting the image details andtranslating them to the user's brain, while image(s) of lower pixeldensity (angular resolution) are provided to regions (parafovea) of theretina having lower perception abilities.

Similarly, certain embodiments of the present invention take advantageof the fact that the perception of color depth is much more eminent inthe foveal region of the eye retina, than in other (parafoveal) regions.In those embodiments, image portions that are projected on the fovea,are projected with higher color depth than image portions that areprojected on the periphery.

Thus, according to certain embodiments of the present invention, certainportions of the image are projected with high image projection quality(high angular resolution and/or high color depth) on certain regions ofthe retina (i.e. on the fovea) that are capable of perceiving projectedimages with high DPI and/or with high color depth, and certain otherportions of the image are projected with lower image projection qualityon regions of the retina, where perception is limited to lower DPIsand/or to lower color depth (e.g. peripheral/parafoveal regions of theretina).

Accordingly, some embodiments of the present invention utilize two ormore image projection modules/units, having different, respectively wideand narrow, angular spread. The image projection module, with the narrowangular spread (e.g. covering solid angle of 3° to 10° along each of thehorizontal and the vertical axes) is configured and operable to projectimages of higher image projection quality (higher angular-resolution/DPIand/or higher color depth) on the central (fovea) region of the retinaso that the user can perceive high quality images. The image projectionmodule, with wide angular spread (e.g. covering solid angle of between60° and 170° along each of the horizontal and vertical axes), isconfigured for projection of image portions with lower image projectionquality on the periphery of the retina (e.g. the so called parafovealarea). This allows to exploit the anatomical properties of the humaneye, to project an image with perceived high quality thereto, whilereducing the amount of data and processing requirements, and/or thesize/weight and/or cost of the system, which would have been required incases where the image would have been projected with the same highquality uniformly across the retina.

Accordingly, the technique of the present invention dramatically reducesdata transfer and processing requirement of the eye projection system,while maximizing user experience from the projection system (the userstill perceives high resolution images through regions of the retinacapable of doing so).

As is known, the retina's inner coating of the human eye has lightsensitive tissue. A region of the retina called the fovea is responsiblefor sharp vision, having a high density of cone-type photosensitivenerve cells. To this end, the technique of the present inventionutilizes high resolution images directed at the user's fovea whileproviding peripheral images directed at the retina and having lowerimage resolution to reduce rendering complexity while maintaining alarge field of view. Therefore, the technique of the invention focusesimage projection with high resolution at the fovea, and providesprojection with lower resolution, thus providing high resolutionprojection with reduced processing and data transmission requirement ascompared to uniform pixel density rendering.

The eye projection system of the present invention includes an opticalmodule configured to direct images (i.e. also referred to herein asimage portions) from at least two (e.g. first and second) imageprojecting units into the user's eye (i.e. at least into one eye). Theoptical module is configured to direct an image portion provided from afirst projection unit into a first region of the user's eye (fovea), andan image portion projected by other projection unit(s) (e.g. the secondprojection unit, or additional ones, if used) to surrounding/peripheralregions of the retina (parafovea).

According to some embodiments, the optical module may generally comprisea combining unit (e.g. beam combiner), and a relay unit (optical relay),which may be arranged in cascading order along an optical path of theoptical module to direct image projections from the image projectionunits and project them in combination (simultaneously or not) into theuser's eye. More specifically, the combining unit combines light beamsassociated with the projected image portions generated by the at leastfirst and second projection units into a combined optical fieldrepresenting the full projection image frame(s) that should beprovided/projected to the user's eye. Here the phrase optical field andcombined optical field are used to designate the intensity profile andpossibly the chromatic content of light measured across the optical pathof image projection towards the eye. The light beams forming thecombined optical field may be transmitted from the combining unit to theoptical relay, which directs the optical field to the user's eye.

More specifically, in some embodiments, the optical relay is configuredto relay to the optical field such that it is directly projected on theretina. Examples of configurations and methods of operation of suchoptical modules including such relays which are configured and operablefor direct projection of images onto the eye retina, and which may beincorporated in the optical module of the present invention, aredescribed for example in PCT patent publication No. WO 2015/132775 andin IL patent application No. 241033, both co-assigned to the assignee ofthe present patent application and incorporated herein by reference.

In this connection, it should be understood that the term directprojection as used hereinbelow relates to projection of an optical fieldsuch that the propagating optical field is focused to an image plane onthe user's retina. For instance, the optical module and/or the opticalrelay thereof may be configured such that the light beams of the opticalfield arrive at the eye lens such that they are substantially collimatedand/or so that they are focused on the retina by the eye lens itself.Alternatively or additionally, such direct projection may be achieved byprojecting the light field towards the retina such that itscross-section diameter is substantially (e.g. twice or more) smallerthan the entrance pupil of the eye (to thereby obtain high depth offield of the image projection on the retina).

In some embodiments the optical module includes a trajectory module(e.g. moveable or rotatable light deflector(s) for instance presenting agaze tracking optical deflector and/or pupil position optical deflectorsuch as those described in IL patent application No. 241033), which isconfigured and operable for adjusting the optical path of the imageprojection in accordance with line of sight (LOS) of the user's eye. Tothis end the system may utilize, and/or may include, an eye trackingunit configured to detect the LOS of the user's eye and/or variation ingaze direction, and provide corresponding data to the trajectory moduleto vary orientation of the general optical path to determine deflectionof optical path provided by the trajectory module. Accordingly, theimage(s) (optical field) may be projected by the system along thegeneral optical path that changes in accordance with changes in theorientation of the line of sight (LOS) of the eye, and/or changes in thepupil's/eye's position relative to the eye projection system. To thisend, the trajectory module may be configured to vary the general opticalpath of light propagation along the optical module in accordance withorientation of the user's eye relative to the eye projection system(e.g. in accordance with the direction of the optical-axis/line-of-sight(LOS) of the eye). Examples of such an optical system including anoptical relay, and eye tracking optical deflectors (e.g. pupil positionbeam deflector and gaze direction beam deflector), which can be used todirect image projection to the eye retina while the eye's position andits gaze direction may vary with respect to the eye projection system,are described for instance in IL patent application No. 241033 which isco-assigned to the assignee of the present patent application andincorporated herein by reference.

To this end, with the use of the trajectory module, eye tracking unitand the optical relay unit, the optical path of the optical module canbe varied such that the optical field combined with the two or moreimage portions, may be transmitted along the general optical pathtowards the user's pupil. The projected light field can be directed toarrive at the pupil's location from a variety of angular orientations,such that the user's eye may form the combined image on the properlocation on the retina, while the user may change his gaze directionand/or while the relative displacement between the eye projection systemand the eye changes. As described above, the optical field is configuredsuch that an image portion generated by the first projection unit formsa portion of the image on a selected part of the retina (i.e. the fovea)and image portions generated by the one or more second projection unitsform portion(s) of the image on other regions of the retina(parafoveal). Further, the location of the generated image portion(s) onthe retina may be kept fixed, even if the user shifts his gazedirection.

Thus, optical relay (also referred to herein as a relay unit) isgenerally configured to generate an image on the user's retina such thatimage portions provided by the first projecting unit are generated onthe fovea region of the retina and image portions provided by the otherprojecting unit(s) is/are generated on the parafoveal region of theretina, being at the periphery of the retina.

It should be noted that the first and second image projection units maygenerally have different properties. For instance, in order to projectthe different fields of view, the image projection units may beconfigured and operable for outputting towards the optical modules lightrays/beams spanning different angular extents. Also they may beconfigured to output images with different angular resolutions and/ordifferent color depth. For instance the first image projection unit maybe adapted to provide RGB images (image portions) with high angularresolution and high color depth, and the second image projection unitmay be adapted to provide RGB image portions with lower color depth, orin some case monochromatic, and/or image portions with lower angularresolution. Variation in color depth may be such that the firstprojection unit provides image with color depth of e.g. 32 bit or 24 bitand the one or more second projection units provide images with colordepth of e.g. 16 bit or 8 bit.

To this end, in some cases the first and second image projection unitsmay be configured based on different technologies. For instance, thefirst image projection unit may be configured as a scanning imageprojection whose outputted image is produced by scanning (e.g.rastering) light rays over the angular extent through which the image isoutputted while modulating the intensity and possibly the color contentof the light rays to create, and output towards the optical module, afirst optical field encoding an image (image portion) generated thereby.Using scanning based image projection may be advantageous in terms ofpower and intensity over non scanning based (e.g. SLM based) projectionunits. The second image projection unit may be configured as either ascanning image projection system as described above, or as an area imageprojection system utilizing one or more spatial light modulators (SLMs;such liquid crystal array and/or micro-mirror array) to simultaneouslymodulate the intensities and possible chromatic content of the pluralityof pixels projected thereby. Examples of configurations and operationsof image projection units using raster scanning and/or spatial lightmodulation to form images are generally known in the art of imageprojection, and the principles of their configurations and operationsneed not be described herein in detail.

It should be noted that according to the present invention the first andsecond image projection units are configured and operable such that theyare capable of respectively outputting two, first and second,complementary image portions (optical fields) which spatially complementone another to form projection of a continuous image on the surface ofthe retina. To this end, the first image projection unit may be adaptedto project an image covering a certain angular/lateral extent about thegeneral optical axis of the optical module such that when it is directedto the retina it falls on the foveal region thereof. The second imageprojection system may be configured and operable to cover a widerangular/lateral field extending about the general optical axis, whileoptionally spanning/covering an annular (or more generally frame ordonut like region) about the general optical axis of the optical module,so that when an image portion created thereby is directed to the retina,it falls at least on the periphery of the retina.

In this regard the first and second image projection units areconfigured to generate image portions that spatially complement oneanother (e.g. such that they overlap or have a common boundary) toenable the optical module to appropriately combine the resulting opticalfields (image portions). The resulting combined optical fieldcorresponds to the foveal image portion at a central region (at an imageplane) thereof and parafoveal image portion at a peripheral portionthereof (at an image plane), providing together a spatially continuousimage having substantially smooth transition between the image portions.To achieve this, the first and second image projections are arranged inthe eye projection system such that the image portions outputted andcombined by the combiner unit propagate with the spatial registrationrelative to one another along the optical path of the optical module.

It should be noted that in some embodiments of the present invention thesecond image projection unit is configured and operable such thatlateral/angular extent of the second (e.g. annular) image portion(optical field) which is outputted thereby to propagate along theoptical path of the optical module, spatially overlaps the first (e.g.central) image portion (optical field), which is outputted by the firstprojection unit to propagate along the optical path. To this end, someoverlap between the first and second image portions, at least along theperiphery (annular boundary) of the first image portion may be used toprovide smooth and seamless transition between the high quality of thefirst image portion and the lower quality of the second image portion.

This technique of the present invention reduces rendering processes bydirecting the required computing power to generate high resolutionimages for the center field of view corresponding to the regions onwhich the user is fixating. The periphery of the image and of the user'sfield of view may be rendered and projected at lower resolution. This issince the parafoveal part of the projected image is at the periphery ofthe user's attention and is captured by the parafoveal region (hereinreferred to as the retina in general) of the user's eye where thephotoreceptor cells are of lower density and provide data with reducedspatial density and lower resolution.

It should be noted that as the images directed into the user's eye aregenerally rendered in accordance with the orientation of the eye, andtransmission of the image/light field is adjusted by the eye trackingunit, the user can experience complete virtual reality (or augmentedreality) perceiving a large field of view (with effectively no imageboundaries) providing a sense of presence to the user.

Thus according to a broad aspect of the invention, there is provided asystem for use in retinal image projection comprising:

at least a first and a second image projection unit configured andoperable for projection of at least a first and a second image portionrespectively; and

an eye projection optical module optically coupled to the at least firstand second image projecting units and configured and operable to combineoptical paths of projection of the at least first and second imageprojection units along a general optical path along which to light beamsfrom said first and a second image projection units, associated withprojection of said projection of said first and a second image portionsrespectively, are to be directed to propagate towards a user's eye toproject a combined image comprising said first and second image portionson the retina.

According to some embodiments, the first and second image projectionunits and said eye projection optical module may be configured andoperable such that the first image portion, projected by the first imageprojection unit, is directed onto a first, central, region on a retinaof the user's eye, and the second image portion projected by the secondimage projection unit is directed onto a second, annular, region at theperiphery of the retina.

In some embodiments, the second image projection unit may be configuredto project the second image portion with an angular extent larger thanan angular extent of the first image portion projected by the firstimage projection unit.

In some embodiments, the first image projection unit may be configuredto project the first image portion, on a first, central, region of theretina, such that it covers a foveal region of the retina and the secondregion covers at least a portion of a parafoveal region of the retinasurrounding said foveal region.

The first and second projection units may further be configured andoperable to allow projection of image portions of relatively higherimage projection quality on the foveal region of the retina and imageportions of relatively lower image projection quality on peripheralregions of the retina. The image projection quality may be associatedwith at least one of the following: angular resolution, and color depth,of the image projection.

According to some embodiments, at least one of the first and secondimage projection units may be a scanning based image projecting unitconfigured and operable for projecting images by scanning an imageencoded light beam on the retina.

According to some embodiments, the system may further comprise a controlunit associated with an eye tracking module configured and operable fordetecting changes in a gaze direction of the eye; and wherein said eyeprojection optical module comprises a trajectory module configured andoperable for adjusting a general optical path of the image projectiontowards the eye; said control unit is adapted to operate said trajectorymodule in accordance with detected changes in the gaze direction.

The eye tracking module may be configured and operable for detectingchanges in a lateral location of a pupil of the eye relative to thesystem, and said control unit is adapted to operate said trajectorymodule in accordance with detected changes in said lateral location ofthe pupil.

The control unit may be configured and operable for operating saidtrajectory module to compensate for said detected changes and therebymaintain the combined image projected at a fixed location on the retina.

According to some embodiments, said eye projection optical module isconfigured to direct the input light into the user's eye and toward theretina through the pupil such that a cross section of the light field(e.g. at full width half max, or at 25% intensity) is smaller than theuser's pupil. This provides an eye-box having diameter smaller withrespect to the user's pupil. The eye projection optical module may beconfigured for varying at least one of location and angle of the eye-boxin accordance with data on the gaze location of the user's pupilreceived from the eye tracking module, to thereby align said exit pupilwith the optical axis of a user's eye.

According to yet another embodiment, the system may also comprise acontrol unit, configured and operable for obtaining imagery dataindicative of a content of combined image that should be projected tothe user's eye, and segmenting said imagery data to said at least firstand second image portions such that the first and second image portionsare complementary image portions projectable by said first and secondimage projection units on to the central and periphery regions of theretina to thereby project said combined image on the retina.

The optical projection module may comprise an optical combining elementconfigured to combine image projection of the first and second imageprojection units such that a first optical field generated by the firstimage projecting unit and associated with the projection of said firstimage portion propagates along a central region of a plane perpendicularto an optical axis of said optical projection module and second opticalfield generated by the second projecting unit propagates at a peripheralregion of said plane with respect to said central region.

According to some embodiments, the system may be configured and operablesuch that said first optical field propagating along the central regionis projected towards the eye such that it covers a central part of thefield of view of the eye thereby providing image projection to thefoveal region of the retina, and said second optical field whichpropagates at the periphery of the optical path covers an annular regionof the field of view, thereby providing image projection to theparafoveal region of the retina.

The first and second optical fields may be projected with respectivelyhigher and lower image projection quality, and the second projectingunit is configured to provide image projection onto a donut-shaped fieldof view thereby providing image projection to the parafoveal region.

Additionally or alternatively, the first and second optical fields mayoverlap at a boundary region between said central and peripheral regionsthereby providing projection of overlapping parts of the first andsecond image portions in the boundary region. The first and second imageportions may be registered such that said overlapping parts projected bythe first and second image projection units correspond to the similarimage content.

According to some embodiments, the system may be configured such thateach of said at least first and second projecting units is configured toprovide output light corresponding to image being projected withprojection angle range nmax, said optical projection module beingconfigured to relay said output light towards a user's eye such thatimages projected by said first and second projecting unit enter saiduser's pupil at angular ranges α¹ _(in) and α² _(in) respectively, anda² _(in)>α¹ _(in). α¹ _(in) may correspond to an angular range of 3°; α²_(in) may correspond to an angular range greater than 200. According tosome embodiments, the system may be configured for use in a head mounteddisplay unit.

According to some embodiments, the system may be configured to providevirtual or augmented reality experience.

In some embodiments, the eye projection optical module may be configuredto direct images projected by the first and second projecting units tothe user's eye while blocking surrounding ambient light.

In some embodiments, the eye projection optical module may be configuredto direct images projected by the first and second projecting units tothe user's eye while allowing transmission of surrounding ambient light,thereby providing a transparent display.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the subject matter that is disclosedherein and to exemplify how it may be carried out in practice,embodiments will now be described, by way of non-limiting example only,with reference to the accompanying drawings, in which:

FIGS. 1A and 1B show schematic illustrations of an eye projection systemand general control unit operations for operating the eye projectionsystem according to the present invention;

FIG. 2 shows a schematic illustration of a human eye;

FIG. 3 illustrates schematically image arrangement generated accordingto the technique of the present invention;

FIG. 4 shows a configuration of the eye projection system according tosome embodiments of the present invention;

FIG. 5 shows one other configuration of the eye projection systemaccording to some other embodiments of the present invention;

FIG. 6 illustrates some image rendering concepts used in the eyeprojection system according to some embodiments of the presentinvention.

DETAILED DESCRIPTION OF EMBODIMENTS

As indicated above, there is a need in the art for novel configurationof an eye projection system. Reference is made together to FIGS. 1A and1B illustrating schematically eye projection system 100 and method 250for projection of an image into a user's eye according to someembodiments of the present invention. The eye projection system 100 isconfigured to generate images and project the generated images into auser's eye 10. For simplicity, a single eye is shown in thisillustration; however it should be understood that generally the imageprojections system 100 may be configured to project images to both theuser's eyes, while allowing certain differences between the right eyeimages and the left eye images, to provide three dimensionalexperiences.

Eye projection system 100 includes at least first 130 and second 140image projection units/modules (hereinafter also referred to asprojection units), and an optical module 120 configured to direct lightcorresponding to images projected by the projection units into theuser's eye 10 to form images on the user's retina 12. The system maygenerally also include, or be connectable to, at least one control unit200. The control unit 200 is typically configured to render image dataand transmit it to be projected by the first and second projection units130 and 140.

To this end, rendering image data to be projected by the two or more(first and second) projection units 130 and 140 may include carrying outthe operations of method 250 as described forthwith. The control unit200 may be configured and operable for carrying out operation 251 forreceiving imagery data indicative of the content of a “projection imageframe” (also referred to herein as combined image) that should beprojected to the user's eye. The imagery data may, for example, includea content and layout of image(s) that should be projected onto theretina (where the content may be information of one or more images thatshould be simultaneously projected onto the retina, and the layout mayinclude information about the arrangement/layout of the projection ofthese one or more images). The layout data may include for examplelateral positioning data indicative of the lateral position of theimage(s) on the retina (e.g. data about an anchor point in the image(s)representing a point of intersection between the LOS of the eye and theimage plane). The control unit 200 may be adapted to carry out optionaloperation 252 for processing the imagery data to determine/produce a“projection image frame” indicative of the combined optical field (imagecontent) that should be projected onto the retina. For instance, in somecases the “projection image frame” is formed by concatenating aplurality of images that are included in the image data, while arrangingthem in the frame in accordance with the layout data. In optionaloperation 253, the control unit performs a registration operation toregister the “projection image frame” relative to the optical axis (LOS)of the eye. In other words, registration/alignment data indicative ofaligned position of the “projection image frame” is relative to the LOSof the eye (e.g. registration/alignment data may be indicative of apoint in the “projection image frame” which should be intersected by theLOS axis of the eye).

In operation 254, the control unit 200 segments the “projection imageframe” into two or more segments (image portions), which are to beprojected by the two or more (first and second) image projection units,130 and 140. At least one of the image projection units, e.g. 130, isadapted for projection of images (image portions) onto the central(foveal) region of the retina; and at least one other of the imageprojection units, e.g. 140, is adapted for projection of images (imageportions) onto the periphery (parafoveal) region of the retina.Accordingly, in operation 254, the control unit 200 utilizes theregistration/alignment data obtained in 253 and segments the “projectionimage frame” into at least two image portions, which are to berespectively projected by the first and second image projection units,130 and 140, onto the foveal and parafoveal regions of the retina. Inthis regard it should be noted that for carrying out such segmentation,the control unit may utilize projection unit configuration data which isindicative of the projection parameters, such as the numerical apertures(NAs), of the first and second image projection units, 130 and 140(namely data about the regions of the retina which are covered by eachof the projection units and their angular-extents). This allows thecontrol unit 200 to properly segment and divide the “projection imageframe” between image projection units, 130 and 140.

In 255 the control unit 200 carries out rendering of the first andsecond image portions that are to be projected by the image projectionunits, 130 and 140, respectively. The control unit 200 may utilize theprojection unit configuration data, which may be indicative ofprojection parameters such as angular resolution and color depthsprovided by the image projection units 130 and 140, to render therespective first and second image portions accordingly. In this regard,as indicated above, the first image projection unit 130, which isconfigured for projection of images to the foveal region of the retina,may be configured for projecting images on the retina with higherangular resolution (higher DPI) and/or with improved color depth, thanthe angular resolution (DPI) and/or the color depth provided by thesecond of the image projection units, 140, which projects images on aparafoveal region of the retina. Then in operation 256, the control unitprovides rendering data indicative of the first and second imageportions to the first and second image projection units, 130 and 140,for projection thereby. In this connection, the eye projection system100 according to the present invention utilizes features of the anatomicstructure of the human eye. Reference is made to FIG. 2 illustrating theanatomic structure of a human eye. As the structure of the human eye isgenerally known, it will not be described herein in detail, but itssuffices to state that the retina (12 in FIG. 1) is the photosensitiveregion collecting light and generating data to be transmitted to thebrain. The retina includes a plurality of photosensitive cells beingsensitive to light intensity (black and white vision) and to wavelength(colour vision). More specifically, the retina includes rod type cells(rods) that are sensitive to luminosity (intensity of light) and conetype cells (cones) that are sensitive to chroma (colors or wavelengths).A region in the center of the retina includes greater concentration ofcone cells (wavelength sensitive cells) and is known as the fovea(marked as 14 in FIG. 1). The fovea is in charge of providing detailedimages of what is located at the center of the field of view, or thecenter of attention. Generally the foveal region provides higher spatialfrequency or higher resolution, and possibly higher color sensingabilities, while the parafoveal region provides low resolution imageperception (providing the brain with blurred indication on the peripheryof the scene) and possibly lower color sensing abilities, while beingmore sensitive to movement and gradients within an input light field.

Accordingly, the image projection units 130 and 140 are configured andoperable for projection of complementary portions of the combinedoptical field (“projection image frame”) that is to be projected ontothe retina. The first image projection unit 130 is configured andoperable such that it can project a first image portion, which is to bedirected to the foveal region of the retina, with high image projectionquality (i.e. rendering/projecting the first image portion, such that ithas a high angular resolution and/or high color depth). The second imageprojection unit is configured for projecting the second image portion(which is to be directed to the parafoveal region of the retina, withlower image projection quality (i.e. reduced angular resolution and/orreduced color depth as compared to those of the first image portion).

For instance the image projection unit 130 may be configured andoperable for projecting certain portion(s) of the projection image framewith high angular resolution, which is about or below 4 arc-minute² ofsolid angle per pixel. The image projection unit 140 may be configuredand operable for projecting certain portion(s) of the projection imageframe with low angular resolution, which is about or above 10arc-minute² of solid angle per pixel. In some embodiments the imageprojection unit 130 is configured for projecting its respective imageportions with RGB color contents (e.g. with color depth of at least 8bit (256 colors) or higher (e.g. 24 bit)). The image projection unit140, which is used for projecting images onto the periphery of theretina, may be configured for projecting its respective image portionswith lower color depths (e.g. 4 bit color depth (16 colors)) and/or withno, or minimal, color information (e.g. gray scale image).

To this end, according to some embodiments of the present invention theimage projection unit 130 may be configured in a scanning imageprojection configuration, (by which an image is projected via scanning(raster scanning) a light beam temporally modulated with the imageinformation, on the projection surface (namely on the respective fovealregion of the retina). Such scanning image projection configuration ofthe image projection unit 130 facilitates achieving high quality imageprojections with compact dimensions of the image projection unit 130.The image projection unit 140 may be configured in either a scanningimage projection configuration; and/or an aerial image projectiontechnique, e.g. which utilizes a spatial light modulator to project itsrespective image portions onto the parafoveal regions of the retina.

The optical module 120 is configured to combine image portions projectedby the at least first and second projecting units 130 and 140 and directthe corresponding light ray to form images projected into the user's eye10 simultaneously. Additionally, the optical module is configured todirect images generated by different projecting units onto differentregions (e.g. foveal and parafoveal regions) of the user's retina 12.

In this regard, it should be noted that according to some embodiments ofthe invention, in the segmentation operation 254 of method 250, thecontrol unit 200 segments the “projection image frame” into two (ormore) segments (first and second image portions), which have someoverlap along a boundary region between them. Accordingly, in suchembodiments, the first and second image projection units, 130 and 140,are configured and operable to project these first and second imageportions onto the retina such that they overlap at the boundary areabetween them. Thus, on the boundary, similar image information isprojected in an overlap and with respectively high and low imageprojection quality, by the first and second image projection units 130and 140. The optical module 120 may be configured to combine imageportions generated by the first 130 and second 140 projection units suchthat the overlap between the first and second image portions ismaintained. Further, the optical module may be configured and/oroperable to direct the projected image portions such that the boundarybetween the image portions substantially corresponds to the anatomicalboundaries of the fovea in the user's retina. The system may include asetting parameter relating to relative size/angular-extend of the fovealimage and boundary location for user's selection, or may be fixed to fitthe anatomy of a majority of users. Overlapping between image portionsis typically provided to facilitate perceived smooth transition betweenthe higher quality of the image projected on the foveal region of theretina and the lower quality of the image portions projected on theparafoveal region(s) thereof, and/or to compensate for inaccuracies andanatomical variations between users.

The control unit 200 may also be responsive to eye tracking data (e.g.obtained from an eye tracking module such as that disclosed in IL patentapplication No. 241033) on eye 10 orientation and/or position, andprovide appropriate commands to the optical module 120 to vary thegeneral path of image projection in order to correct the optical path ofimage projection in accordance with the eye's 10 movements. Forinstance, the optical module 120 may include a trajectory module (e.g.such as 124 shown in FIG. 5) which may include for instance anadjustable gaze tracking beam deflector and/or an adjustable pupilposition beam deflector (e.g. which may be configured and operable asdescribed in IL patent application No. 241033). The control unit 200 maybe configured and operable for adjusting positions of one or both ofthese deflectors to vary the general propagation path of imageprojection in accordance with the gaze direction (direction of the LOS)of the eye, and/or the relative lateral displacement and/or relativeangular orientation between the optical axis of the eye and the outputoptical axis of the optical module 120; e.g. to maintain substantiallyfixed relative orientation and/or displacement between them. Indeed,when fixed relative orientation and displacement are maintained betweenthe optical axis of the eye and the output optical axis of the opticalmodule 120, the image(s)/image portions from the first 130 and second140 projection units are projected at fixed location(s) on the retina.

Alternatively or additionally, in some embodiments, the control unit 200may be configured and operable to compensate for some/slightchanges/shifts in the relative orientation and/or displacement betweenthe optical axes of the eye and the optical module 120, by operating thefirst and second projection units 130 and 140 to shift and/or warp theimage projected thereby so that the projected optical field isshifted/warped in ways that counteract changes in the relativeorientation/displacement. For instance, use of such a technique tocompensate for small eye movements is exemplified in more detail belowwith reference to FIG. 6.

Thus, the eye projection system according to the present invention isgenerally configured to provide image projection with increasedresolution to the foveal region of the retina, while providing imageprojection with relatively lower (e.g. normal) resolution to theparafoveal region surrounding the fovea. This enables the system toreduce complexity of image rendering/processing with respect to imagesof high resolution, while providing high resolution images to regions ofthe user's eye that will actually utilize the high resolution image andrequire it.

FIG. 3 illustrates a two-portion image generated by the eye projectionsystem of the invention. The complete image includes two image portions(generally at least two as the periphery image portion may be composedof several sub-images generated by several projection units) includingthe parafoveal/retinal image portion 1400 providing peripheral imagedata, which generally surrounds the center of attention; and the fovealimage portion 1300 providing the main part of the image data and whichcorresponds to the center of attention of the user. The foveal imageportion 1300 may typically be of higher resolution with respect to theparafoveal image portion 1400. The actual number of pixels of the fovealportion 1300 and the parafoveal portion 1400 may be the same or higher.The difference in image resolution may typically be provided due to adifferent area (field of view) covered by each image portion.Specifically, the foveal image portion may generally be projected tocover the actual area of the fovea, or a lightly larger area, which issignificantly smaller with respect to the surrounding area of theretina. It should be noted that the image portions as shown in FIG. 3exemplify a circular field of view. However, generally the field of viewmay be rectangular, oval or of any other shape. The foveal region 1300of the projected image may preferably be of circular shape or oval so asto cover the field of view of the fovea and thus optimize the sharpvision abilities of this region of the eye. Also exemplified in FIG. 3is an angular range of the foveal 1300 and parafoveal 1400 imageportions at the user's pupil. Typically the angular range of the fovealimage portion may be α¹ _(in) and may be between 3° and 10°, andpreferably about 5°. Additionally, the angular range of the parafovealimage portion at the pupil input may be higher than 20°, and typicallyabout 120°-180°.

Referring to FIG. 4 and FIG. 5, two configurations of the eye projectionsystem 100 are shown, exemplifying more specific configurations of theoptical module 120 according to two exemplary embodiments of theinvention. As shown in FIG. 4, the first 130 and second 140 projectingunits are associated with corresponding initial relay modules 122 a and122 b respectively. In the example of FIG. 5 the relay modules arecombined to single relay module 122 including two (generally at leasttwo) input lenses L1 a and L1 b and a single output lens L2. As shown inboth the examples of FIG. 4 and FIG. 5, the optical system 120 maypreferably include a combining module (M or M1 and M2), first 122 andsecond 126 relay modules and a tracking/trajectory module 124. In thisconnection, the first relay module, including separate relay modules asin FIG. 4 or a combined relay module as in FIG. 5, is configured tomerge image projections generated by the first 130 and second 140projecting units (or additional projecting units being merged inparallel or in cascade) such that each projecting unit transmits lightto form an image portion (i.e. an optical field) in a correspondingregion along a cross section perpendicular to the general direction ofpropagation of projected light. Additionally, FIG. 4 illustrates outputangular range aumx of the first 130 and second 140 projecting units. Asindicated, the first 130 and second 140 projecting units may or may notprovide a similar output angular range. The optical system 120 isconfigured to adjust the angular range of each projecting unit asdescribed in FIG. 3 above.

Referring to FIG. 4, each of the first 130 and second 140 projectingunits outputs light indicative of an image or an image stream, marked inthe figures by extreme light rays R1 a, and R1 b for the firstprojecting unit 130, and R2 a and R2 b for the second projecting unit140. The output light from the first projecting unit 130 is transmittedinto input lens of relay module 122 a and is relayed onto trajectorymodule 124. More specifically, the light rays are output from theprojecting unit such that different pixels, or different points on theprojected image, are associated with corresponding different angles oflight propagations. Thus the extreme light rays R1 a and R1 b correspondto two extreme points on the projected image. First lens L1 a of therelay unit 122 a refracts the light and directs it towards second lensL2 a which re-focuses the input light onto the trajectory module 124. Atthe output of relay unit 122 a, one or more beam combiners, M1 and M2are located, as exemplified in the figure. The beam combiners M1 and M2are configured to combine light projected by the first projecting unitinto the optical path of light projected by the second projecting unit140. Similarly, relay unit 122 b typically includes first and secondlenses L2 a and L2 b and is configured to relay light projection fromthe second projecting unit 140 in a substantially similar manner.Exemplary light rays R2 a and R2 b illustrate the extreme light rays ofprojection unit 140. Generally, the relay units 122 a and 122 b areconfigured with appropriately selected different optical powers of thelenses thereof and beam combiners M1 and M2 are located such that imagesprojected by the first projecting unit 130 take a smaller area at acenter of a region of image projection, surrounded by portions of imagesprojected by the second projecting unit 140 as exemplified in FIG. 3.Further, it should be noted that generally both relay units 122 a and122 b and the beam combiners M1 and M2 are configured to merge the imageportions to form a common image plane (e.g. on the trajectory unit 124).This is to ensure common focusing of the user's eye.

It should be noted that the relay unit 122 a (as well as any other relayunit such as 122 b and 126, which is not specifically described here,may include additional lenses and are shown here as two-lens relay unitsfor simplicity. It should also be noted the optical parameters of therelay units are selected to provide proper imaging with desiredresolution and sharpness as generally known and/or can be determined bystandard optical design tools.

The projected images generated by the first and second projecting unit130 and 140 are directed onto the trajectory module 124. The trajectorymodule 124 may include, for example, one or more moving lightdeflectors/mirrors (e.g. gaze tracking beam deflector and/or pupilposition beam deflector as discussed above) configured to varyorientation thereof to direct light impinging thereon with a generaloptical path determined in accordance with tracking of eye movement. Thetrajectory module 124 and technique of eye tracking may be of any knownconfiguration, and, as indicated above, an exemplary configuration isdescribed in IL patent application No. 241033 assigned to the assigneeof the present application.

As indicated above, FIG. 5 illustrates an additional configuration ofthe first relay module 122, configured to combine projected images fromthe first and second projecting units 130 and 140 within the relaymodule. The relay module 122 utilizes a common second lens L2 whileutilizing separate first lenses L1 a and L1 b for the first 130 andsecond 140 projection units. As shown, the output from the secondprojecting unit 140 is relayed through lenses L1 b and L2 ontotrajectory module 124. Location and optical power of lenses L1 b and L2is selected to provide angular distribution of the projected light(exemplified by extreme light rays R2 a and R2 b) to provide desiredangular resolution for peripheral vision of the user. Light output ofthe first projecting unit 130, exemplified by extreme light rays R1 aand R1 b, is collected by input lens L1 a converting the diverging lightto a set of parallel light rays propagating towards beam combiner M. Thebeam combiner M, which, as indicated above, may utilize a single surface(e.g. reflecting surface) or a plurality of surfaces, or may beconfigured as a partially reflecting surface (e.g. beam splitter type),is configured to direct output light of the first projecting unit 130 topropagate with and be located at the center of the cross section oflight output from the second projecting unit 140. Generally beamcombiner M may be configured to block light transmission from the secondprojecting unit 140, within the region at the center of the crosssection of the field of view. However, in some configurations, the beamcombiner M may be configured to partially transmit light passingtherethrough, and thus allow at least a portion of light generated bythe second projecting unit 140 to pass at the center of the field ofview. In some further embodiments, beam combiner M may block at acentral region and transmit at the periphery thereof, to allow smoothtransition in image projection between the image generated by the first130 and the second 140 projecting units. The combined projected light isfurther collected by second lens L2 and directed/focused onto thetrajectory module 124.

In this connection it should be noted that the beam combining technique,i.e. utilizing one, two or more beam combiners as in FIGS. 4 and 5, mayprovide certain overlapping between image projection by the firstprojecting unit 130 (foveal image) and image projection by the secondprojecting unit 140 (parafoveal image). To this end the one or more beamcombiners may be configured as beam splitting surfaces providing 50%reflection and 50% transmission of light, and/or as non uniform beamcombiner surfaces having high transmission (reflection) at the peripheryof the surface and high reflection (transmission) at the center of thesurface. Thus, the transition between foveal image and parafoveal imagesmay be made relatively smooth. It should also be noted that the graphicprocessing unit (GPU) may typically be configured to render thedifferent image portions so as to provide smooth transition as describedabove. For example, the GPU may be configured to render images whileadjusting image brightness at image portion boundaries to avoid sharpgradients resulting from image combining.

Generally, according to the present invention as described herein withreference to FIGS. 1, 4 and 5, the first and second projecting units,130 and 140 may be any type of projecting unit, and may preferably beconfigured as scanning laser projecting units. Generally projectionunits of scanning laser type may provide greater efficiency with respectto light intensity, as well as in resolution of the projected images.Typically, the first and second projecting units 130 and 140 may beconfigured with similar specification, while providing projection ofdifferent image data sent for the control unit (200 in FIG. 1) orGraphic Processing Unit (GPU) thereof. Although the optical module isconfigured to combine image projection of the first and secondprojecting units (130 and 140) as generally exemplified in FIG. 3, theimage data provided to the second projection unit 140 may be indicativeof the complete image including the central (foveal) region, or it mayinclude image data corresponding to a donut shaped image (i.e.peripheral image having a hole region where the image projected by thefirst projection unit 130 is combined).

As indicated above, the first and second projecting units (130 and 140)may preferably be scanning laser type projection units. In suchprojection units, a raster light deflector (moving mirror, e.g.utilizing MEMS) is configured to scan a laser beam within an angularscanning range (angular projection range) α_(max). The optical module120 combines and directs the light of the at least first and secondprojecting units such that at the user's pupil, light generated by thefirst projecting unit has angular range α¹ _(in) and light generated bythe second projection unit has angular range α² _(in) larger than α¹_(in). Effectively, different angles of light propagation at the user'spupil correspond to different points within the field of view. This iswhile angular resolution of light projection generally corresponds toresolution of the perceived image. The inventors have found that basedon the anatomy of the human eye, input angular range of light projectionby the first projection unit α¹ _(in) is preferably configured to bewithin a range of about 3°. In some configurations, the optical module120 and the relay module 126 thereof are configured to provide anangular range of about α¹ _(in)=5° to ensure coverage of the fovealregion within the retina. The angular range α¹ _(in) is preferablydetermined in accordance with image resolution provided by the firstprojection unit 130 such that angular resolution at the input pupil ofthe user exceeds 2 arcminutes per pixel, and preferably exceeds 1arcminute per pixel. Contrary to projection by the first projecting unit130, light projection by the second projection unit 140 is generallyconfigured to provide meaningful images within the periphery of thefield of view. Thus, the angular range α² _(in) associated with imageprojection by the second projecting unit 140 is preferably greater than20°, and in some configurations may be greater than 70° to provide theuser image projection with a wide field of view and provide a sense ofpresence within the projected image. The second projection unit 140 mayprovide a similar number of different angular points, such that thelarger the angular range, the lower the angular resolution.

When scanning laser type projection units are used, the laser beam maygenerally include light beams from three or more laser units emittingthree or more primary colors (e.g. red, green and blue) and isconfigured to vary intensity of each of the colors in accordance withthe scanning orientation to provide imaging of a desired image data. Theoptical module 120 is configured to relay the light output from thefirst and second projection units such as to direct the projected lightonto the user's eye. Generally the optical unit, and more specifically,the relay module 126 thereof is configured to direct the input lightinto the user's eye such that a cross section of the light, at theuser's pupil (i.e. eye-box) has a diameter smaller with respect to theuser's pupil. More specifically, the cross section diameter of light(e.g. full width, half max measure, or standard deviation measure) issmaller with respect to pupil diameter in strong lighting conditions.This is while the trajectory module 124 deflects the general opticalpath to vary location and angle of the eye-box (exit pupil of thesystem) in accordance with detected gaze direction (LOS) and/or locationof the pupil (e.g. due to eye/LOS movement relative to the eyeprojection system 100). It should also be noted that output intensity ofthe projecting units, being scanning laser based on non laser or nonscanning, and in some embodiments being spatial light modulator imageprojecting units (e.g. LCD based), is preferably sufficiently low, or isattenuated, to avoid damage and preferably avoid discomfort to the user.

In this connection it should be noted that the direct projectiontechnique used by the optical module 120 according to the presentinvention provides for projecting images onto the eye retina, in amanner that the input light field propagates to an image plane on theretina. This is generally achieved regardless of focusingdistance/configuration of the user's eye (which is generally controlledbased on real or to virtual distance to objects of interest) as theeye-box size, or cross section of the light field at the pupil, isgenerally smaller than pupil diameter. This provides image projectionwith enhanced depth of focus on the retina. Accordingly, the image isprojected to be substantially focused on the retina, at substantiallyany focal state of the eye lens. For example, the image may be projectedwith substantial depth of focus allowing it to remain focused on theretina, while the eye lens is at any focal state within a wide focallength range from 4 meters to ∞.

Generally, according to some embodiments of the present invention, theeye projection system as exemplified in FIGS. 4 and 5, utilizes opticalrelay of the projected images into the user's eyes. In this connection,the technique of the present invention combines the projected images ofthe projection units (e.g. first and second projection units), and thecombined light field passes through the trajectory module 124, trackingeye's movements, and are transmitted to the eye through relay module126. Thus, the optical module 120 may be configured to optimizeprojection with respect to eyes' orientation, illumination conditions,image characteristics, user preferences etc. This is while the differentimage portions projection by the projection units are combined to directimage portions to the corresponding regions in the user's retina. Asindicated above, in some embodiments of the invention, a firstprojection unit provides image projection directed towards the fovealregion in the user's eye, while the second projection unit provides asurrounding image directed at the retina around the fovea. The projectedimages are combined using the one or more beam combiners and the firstrelay module(s). The latter is typically also configured to adjustspreading of the projected images such that the pixel density in the“foveal” image projected by the first projection unit is greater withrespect to the pixel density in the surrounding “retinal” imageprojected by the second projection unit. Generally the foveal image isprojected with resolution corresponding to 480p 720p, 1080p or higheronto an angular portion of the field of view of about 3° to 5° to eachdirection. The parafoveal/retinal image is projected with asubstantially similar number of pixels; however the projected image isrelayed to the user's eye such that it takes a predetermined part of theuser's field of view, while leaving the central region, corresponding tothe foveal image as shown in FIG. 3, with low projection intensity tothereby allow projection of the foveal image by the first projectingunit 130.

Thus configuration of the optical module allows for adjustments of theexit pupil and of the general optical path in accordance with eyetracking and image characteristics. It should also be noted that byproviding high resolution images directed at the fovea with lowerresolution peripheral image data, the system may optimize the experiencewhile reducing computation complexity. Further, in order to compensatefor small eye movement, the Graphic Processing Unit (GPU) associatedwith the eye projection system, may be configured to render image datacorresponding to a region that is slightly greater than the actual imagedata projected. Thus, the rendered image data exists and may be directlytransmitted to the projection units based on the exact location of theeye at the time of projection. This is exemplified in FIG. 6 showing arendered region of the foveal 1300 and retinal 1400 images. Morespecifically, while image data corresponding to regions 1300 and 1400 isprojected into the user's eyes, the GPU processes image data whichcorresponds to the following frame. The GPU generated image datacorresponds to regions 1310 and 1410, which are larger than regions 1300and 1400. Regions 1310 and 1410 include image data that is generallyoutside of the field of view defined by image portions 1300 and 1400,referred to herein as shoulder image data. When, in the newly processedimage, data is transmitted to the projection units (130 and 140), thecontrol unit (200) indicates, using eye tracking technology, what is theexact location of the user's pupil, and the corresponding parts of theprocessed images are projected. This technique enables image variationcompensating for small eye movements by providing already renderedshoulder image data pieces. In this connection, providing highresolution (i.e. below 4 arc-minute² of solid angle per pixel) to thefoveal region of the user's eye in uniform resolution projection,requires generating image data having an extremely large amount ofpixels (full hemisphere image with such spatial resolution requiresalmost 30 Mega pixels). The technique of the present invention allowsfor providing image projection with desirably high perceived angularresolution, while reducing the image resolution to regions of the eyethat are less sensitive. Thus the foveal image utilizes high pixeldensity providing angular resolution of below 4 arcminutes per pixel,while the parafoveal image provides lower angular resolution (e.g. about10 arcminutes per pixel). This allows the control unit and the GPUthereof to generate image data corresponding to lower resolution images,e.g. about 5Mega pixels for foveal images and 5Mega pixels forparafoveal images, providing a total rendered image data of about 10OMega pixels.

Thus the present invention provides a system for image projection to auser's eye. The system is configured to reduce image renderingcomplexity and data transfer from a processing/rendering unit to theprojection unit(s), while providing desirably high resolution images tothe user. The system is generally configured to generate a combinedimage projection based on two or more image portions directed atcorresponding portions of the user's retina, and is configured tooptimally exploit the local sensitivity of the different regions of theretina. Those skilled in the art will readily appreciate that variousmodifications and changes can be applied to the embodiments of theinvention as hereinbefore described without departing from its scopedefined in and by the appended claims.

1. A system for image projection comprising: (a) An image projectoradapted for projection of at least two image portions with differentrespective projection parameters; (b) a processor adapted for receivinginput data indicative of at least one image to be projected, and forprocessing the input data to segment the image data to at least twosegmented image portions and rendering said at least two segmented imageportions according to said different respective projection parameters torespectively generate said at least two image portions for projection bysaid image projector.
 2. The system of claim 1 wherein said at least twoimage portions comprise at least one foveal image portion and at leastone parafoveal image portion; and wherein the image data is segmented toat least a segmented foveal image portion indicative of said fovealimage portion and a segmented parafoveal image portion indicative ofsaid foveal image portion.
 3. The system of claim 2 wherein the imagedata is segmented according to designated portions of said imageintended to be respectively received by foveal and parafoveal regions ofa retina of user's eye.
 4. The system of claim 3 comprising determiningsaid designated portions according to registration/alignment dataindicative of aligned position of the image relative to a line of sight(LOS) of the user's eye.
 5. The system of claim 4, further comprising aneye tracking module and operable for detecting changes in said line ofsight (LOS) of the user's eye thereby enabling to determine saidregistration/alignment data.
 6. The system of claim 2, wherein at leastone of said segmented foveal image portion and said segmented parafovealimage portion corresponds to a region of said image that is larger withrespect to the respective one of the foveal image portion and theparafoveal image portion being projected, thereby rendering thesegmented image portions with shoulder image data.
 7. The system ofclaim 6, further comprising an eye tracking module and operable fordetecting changes in a line of sight of the eye; and wherein saidprocessor utilizes said shoulder image data for projecting the fovealand parafoveal image portions while compensating for small changes onsaid line of sight.
 8. The system of claim 2, wherein said foveal andparafoveal image portions include an overlap at a boundary regionbetween them thereby providing a smooth transition at the boundaryregion, between different respective projection parameters of theprojection of said foveal and parafoveal image portions on the retina.9. The system of claim 8, wherein said processor is adapted forregistering said foveal and parafoveal image portions to provides saidshoulder image data associated with overlapping parts of the foveal andparafoveal image portions to correspond to the similar image content.10. The system of claim 1 wherein the image projector includes at leasttwo image projection modules adapted for projecting said at least twoimage portions respectively.
 11. The system of claim 10, comprising aneye projection optical module optically coupled to the two or more imageprojection modules and configured and operable to combine optical pathsof projection of the image projection modules along a general opticalpath along which light beams from said first and a second imageprojection units are directed to propagate towards a user's eye.
 12. Thesystem of claim 11 wherein said two or more image projection modules andsaid eye projection optical module are configured and operable such thata foveal image portion, projected by a first image projection module, isdirected onto a central region of image projection, and a parafovealimage portion, projected by a second image projection module, isdirected onto a second, annular, region surrounding said central regionof image projection.
 13. The system of claim 2 wherein said parafovealimage portion has an angular extent larger than an angular extent of thefoveal image portion.
 14. The system of claim 2, wherein said fovealimage portion has higher image projection quality with respect to saidparafoveal image portion.
 15. The system of claim 2 wherein said fovealimage portion has higher color depth with respect to said parafovealimage portion.
 16. The system of claim 1 wherein said processorcomprises a graphical processing unit (GPU).
 17. A method comprising:(a) providing input image data and processing the input image data bysegmenting the image data to at least two segmented image portions; (b)rendering the at least two segmented image portions with selecteddifferent respective projections parameters and generating at least twoimage data portions; (c) providing output data comprising said at leasttwo image data portions to be projected by a corresponding imageprojector.
 18. The method of claim 17, wherein said at least two imageportions comprise at least one foveal image portion and at least oneparafoveal image portion; and wherein the image data is segmented to atleast a segmented foveal image portion indicative of said foveal imageportion and a segmented parafoveal image portion indicative of saidfoveal image portion.
 19. The method of claim 18, wherein at least oneof said segmented foveal image portion and said segmented parafovealimage portion corresponds to a region of said image that is larger withrespect to the respective one of the foveal image portion and theparafoveal image portion being projected, thereby rendering thesegmented image portions with shoulder image data.
 20. The method ofclaim 18, wherein said foveal and parafoveal image portions include anoverlap at a boundary region between them thereby providing a smoothtransition at the boundary region, between different respectiveprojection parameters of the projection of said foveal and parafovealimage portions on the retina.